Plastics possess a proper combination of chemical, physical, and electrical properties to render them probably the most versatile raw materials available to mankind. Moreover, the plastic deformable state achieved by thermoplastic polymers at elevated temperatures allows them to be shaped into an endless variety of finished products. Finished products of great geometrical complexity can be formed using thermoplastics as the raw material. Plastic resins offer a very great advantage over other raw materials, such as metals, wood, and ceramics, in that they can be easily shaped into useful objects. The shaping of plastic resins into useful articles is relatively quick and is superbly fit for mass production without necessarily sacrificing quality or aesthetics.
Plastic resins are often superior to other materials for use in containers, sealing, toys, pipes, films, component parts, and countless other products. These products are generally formed by employing injection molding, blow molding, or extrusion.
This invention relates to a new polymer that can be employed as a thermoplastic resin. This polymer is synthesized by the copolymerization of meta-diisopropenylbenzene or para-diisopropenylbenzene with certain electron rich aromatic compounds.
The polymerization of diisopropenylbenzene in solution to yield soluble polymers which contain indane groups has been described by Brunner et al. (J. Polymer Sci. 28, 629 (1958). They employed Lewis acid type polymerization catalysts to produce polyindane compositions having softening points of 250.degree. C. and higher. Similarly A. A. D'Onofrio (J. App. Polymer Sci., 8, 521 (1964) has shown that polymerization of diisopropenylbenzene with butyl lithium-titanium tetrachloride-hydrogen chloride catalyst yielded polyindanes with softening points above 268.degree. C. Brunner and Walbridge (Brit. Pat. No. 850,363) show other examples of products obtained from polymerization of diisopropenylbenzene in which the softening points were 222.degree.-230.degree. C., 103.degree.-114.degree. C. and 67.degree.-72.degree. C. The structure of the low softening products was not indicated. U.S. Pat. No. 4,205,160 describes polymers containing units of indane, 1-pentene and 2-pentene structures and which have softening points in the range of from 120.degree. to 200.degree. C., number average molecular weights in the range of 800-2000, and an indane content of from 20 percent to 100 percent.
The cationic hompolymerization of meta-diisopropenylbenzene produces polymers containing predominantly indane structure (polyindanylation). The polymerization occurs by a step-growth process but gels unless the polymerization temperature is kept above 70.degree. C. The gelation is presumed to arise from branches emanating from pendant .alpha.-methylstyrene units which were incorporated through 1,2-vinyl propagation.